Glyceria

The giant species G. maxima (Hartm.) Holmb. is known from adjacent parts of Ontario and may enter Michigan at some point. It is very aggressive, capable of forming large monodominant stands 3–4 m tall from coarse rhizomes. It would key to G. grandis, but differs in having stiffer panicle branches, scabrous lower sheaths, and larger glumes (the lower ca. 2–3 mm long). Glyceria grandis has lax panicle branches, smooth lower sheaths, and shorter glumes, the lower less than 2 mm long.